Method for forming precision receptacles from sheet metal



Dec. 28, 1954 R. c. BURROUGHS METHOD FOR FORMING PRECISION RECEPTACLES FROM SHEET METAL Filed Aug. 5, 1952 2 Sheets-Sheet 1 J on 3 3.3 we iv 5 \QNJ w 9 a U .9 Q I x U E E a Q Q w 9 0 K G U B Q Uv 1 SW H- PUUIW JACIWVL UAW , INVENTOR. QOBEWI' C. Bun-nous ll-bum:

ATTOQMEYS Dec. 28, 1954 R, c. BURROUGHS 2,697,997

METHOD FOR FQRMING PRECISION RECEPTACLES FROM SHEET METAL Fi led Aug. 5, 1952 2 Sheets-Sheet 2 T Fig.7 G4 a? 55 5 Q2 h u G8 5%,; 48 Q3 Tl i 4 INVENTOR. Hosea-r C. Bomzoucus United States Patent F METHOD FOR FORMING PRECISION REQEP TACILES FROM SHEET METAL Robert-C. Burroughs,,Washington, D. C.

Application, August 1952, Serial-No. 302,840

2 (Qlai'ms. (GI; 113-116) This. invention. relatesito a method. of. forming precision receptacles from sheet! metal and more particularly to an improved method; for; transferring dimensions from a working-"drawing, to. a, sheet metal. blank and to a. tool for. carryingout theimproved method.

It isamong the objects. of the invention toprovide an improved. method, for laying, off a diagram ona blank of sheet. metal or other sheet material corresponding, to a: diagramjprovided by a.working. dr,awing by accurately layingtofi on the blank dimensionsgivem on the working drawingto obtain. centers and. points of intersection. and r then scribing linesonthe blank using the centers and intersection. points as guides;,whichenables an' operator to lay off the dimensionsadirectly on. the blankusing straight outside edgesof. the blank for guiding; a measuring, tool; whichenablesthe operator to lay oif. the dimensions directly on. the blank along, lines perpendicular. to the straight. outer edges of the blank. by means. of a single measuringtool and eliminates, the needfor-separate-measuring tools, such: as dividers; separate. scales and. protractors; which, greatly facilitates, andv expedites. the operation of laying off the diagram on. the blank from. the working drawing or blueprint; and to. provide a tool which. is usable along. the outer cdgesof the blank andis adjustable to. compensate for. the distance between: the outer edges of the blank andthe reference lines of. the diagram from which. the dimensions. are measured; which has scales of. lineal measurement on which the dimensions can be read: directly; and. which. is. simple and durable in: construction,. economical. to. manufacture, and effective and efficient in use.

Otherobjects and advantages will become apparent from a, consideration of the: following description and the. appended claims. in conjunction; with: the accompanying, drawings. wherein:

Figure 1. is aplan view of, a working drawingor blueprint for the. blank from. which a precision receptacle is to be formed;

Figure 2 is a plan view of a piece of. sheet metal with the outline of the blank scribed, thereon;.

Figure 3 is a. plan view. of the blank afterit has. been cut: from the sheet metal and illustrates. the manner in which the fold lines are located on. the. blank;

Figure 4 is, a plan view of the blank after the corners have been. cut away between the portions. thereof which are to. form. the side and. end walls. of the receptacle and shows the manner of locatingthe centers and corners of apertures provided in the portion of' the blank which is to constitute the base. of the finished receptacle;

Figure 5 is: a perspective view of the completed blank;

Figure 6 is a top plan view of a measuring, instrument for laying out on the sheet metal blank the dimensions given on the Working drawing; and

Figure 7 is a cross sectional view on the line 74-7 of. Figure 6.

With continued reference to the drawings, the working drawing illustrated in Figure 1 and generally designated at 10 is the usual paper drawing or blueprint and illustratesv the, completed blank with the various dimensions includingv the overall length and width dimensions 11 and 12 of the blank, the length and width dimensions 13 and 14 of the intermediate or base portion 15 of the blank exclusive of the side wall portions 16 and 17 and the end. wall portions. 18 and 19, dimensions as. indicated at 20 and locating the centersof circular apertures in the base portion 15' from two perpendicularly disposed reference lines, 22 and 23 and dimensions, as indicated at 2'4 p 2,697,997 Patented Dec. I 28, 1954 and 25 locating the corners of straight sided or rectangular openings in the base portion of the blank from the same two reference lines 22 and 23 or from the other two perpendicularly disposed reference lines 26 and 26'.

The drawing will carry the radial or diametrical dimensions of all circular openings so that these openings can be easily drilled or punched once the centers have been properly located on the blank and the side and end wall portions of the blank may also have openings therein, the locations of which are measured from the adjacent reference lines. It will be noted that the dimensions loeating the centers of the circular openings and the corners of the straight sided openings are all measured from the inner reference lines rather than from the outer edges of the blank since, in a precision receptacle, such as the chassis of an electronic instrument, it is necessary that the measurements locating the openings in the base of the chassis be held to close tolerances relative to the edges of the base portion and to each other.

In laying out the blank, a piece of suitable sheet metal 27 is placed on a suitable horizontally disposed working surface, such as the top of a table or work bench and a punch mark is made on the sheet metal locating one of the corners, for example the corner 28, of the outline of the blank. A line 29 is then drawn from the corner mark 28 along one edge 30 of the piece of sheet metal and a scale is applied to this line and the dimension 12 on the working drawing is measured off on the line 29.. A punch mark or intersecting line is then made on the sheet metal at a distance along the line 29 from the corner mark 28 corresponding to the dimension 12 to give a second corner 31 of the blank. A square is then applied to the line 29 and a distance is measured off from the corner mark 31 perpendicular to the line 29 corresponding to the dimension 11 on the working drawing to give a third corner 32 of the blank and a line 33 indicating the corresponding side edge of the blank. A-

line 34 is then laid oif from the corner mark 28 also perpendicular to the line 29 and the dimension 11 measured off on this line 34 to give the fourth corner 35 of the blank and a line 36 is scribed from the corner 32 to the corner 35 and measured to be sure that it is of exactly the same length as the line 29. The blank will now have been outlined on the sheet metal and is cut from the sheet metal along the lines 29, 33, 34 and 36 to provide the sheet metal blank, generally indicated at 37 and illustrated in Figure 3.

After the blank 37 has been cut from the sheet metal 27 a special tool, as generally indicated at 40 and illustrated in detail in Figures 6 and 7 is used to locate on the blank 37 the corners of the intermediate base portion 15" of the blank, this tool being subsequently used to measure on the blank the other dimensions given on the working drawing 10.

The tool 40 is an adjustable square and includes a frame 41 of elongated, rectangular shape having a marginal flange 42. extending therearound and a web 43 disposed within. the flange medially of the width of the latter. This frame has spaced apart and substantially parallel straight side edges 4.4 and 45; and has a notch 46 extending across one end thereof between the side edges 44 and 45, the web 43 being thickened at this end of the frame so that portions of the web are disposed at the opposite sides of the notch. Intermediate the width of the frame a tubular boss formation 47 is provided on the web 43 which boss extends from the end of the frame in which the notch 46 isv provided intov an opening 48 provided in the web 43 intermediate the length of the frame. A flat scale 50. extends slidably through the notch 46 and the inner end of the notch isso formed that the straight and parallel longitudinal edges of the scale 50 are maintained exactly perpendicular to the side edges 44 and 45 of the frame 41. The scale 50 has a groove 51 extending from one to the other end medially of the width thereof and a locking pin 52 extends through the bore 53 of the boss 47 from the inner end of the boss and has a portion 54 of reduced thickness. extending past the por tion of the scale: 50 between the bottom or inner end of the notch 46 and, the groove 51 in the scale and terminating in a hook formation 55 engaged in the groove 51. The pin 52 projects at its. end remote from the hook formation 55 from the inner end of the boss 47 and this projecting end portion of the pin is provided with external screw threads 56. A thumb nut 57 is threaded onto the screw threaded portion of the pin 52 and, when tightened on the pin clamps the scale 50 against the inner end of the notch 46 to releasably lock the scale in selected positions of adjustment longitudinally of the scale relative to the frame 41. The scale or scale bar 50 has scales of lineal measurement, as indicated at 58 and 59, extending along the longitudinal edges thereof.

An extension 60 projects outwardly from the end of the frame 41 in which the notch 46 is provided and comprises a pair of plate-like members 61 and 62, of rectangular shape disposed one at each side of the notch 46 and the scale 50 and extending beyond the outer longitudinal edge of this scale. A subframe 63 of rec tangular shape is mounted on the extension 60 at the end of this extension remote from the frame 41 and this subframe has a slot 64 extending longitudinally therethrough and is provided intermediate its length with a tubular boss formation 65 the opposite halves of which are disposed at respectively opposite sides of the slot 64.

A scale bar 66 smaller than the scale bar 50 extends slidably through the subframe 63 and has its side faces disposed substantially in the planes of the corresponding side faces of the scale 50. The scale 66 has its longitudinal edges parallel to the longitudinal edges of the scale 50 and has its longitudinal edge nearest the frame 41 contiguous to the longitudinal edge of the scale 50 remote from the frame.

The scale 66 is provided with a groove 67 extending longitudinally thereof from one end to the other and medially of the width thereof and a locking pin 68 extends into the bore 69 of the subframe 63 from the end of the bore 69 remote from the frame 41 and has a portion of reduced thickness extending past the portion of the scale 66 between the outer longitudinal edge of this scale and the groove 67 and has a hook formation 70 on the end of this portion of reduced thickness engaging in the groove 67 in the scale 68. A portion of the pin 68 projects from the subframe 63 at the end of this subframe remote from the frame 41 and this end of the pin is externally screw threaded, as indicated at 71, and carries a thumb nut 72. A compression spring 73 is interposed between the thumb nut 72 and the adjacent end surface of the subframe 63 and the slot 64 in the subframe has an inner end adjacent the end of the subframe 63 remote from the frame 41, the inner end of the slot 64 being shaped to maintain the scale 66 parallel to the scale 50 and perpendicular to the side edges 44 and 45 H longitudinally thereof through the subframe 63 to selected positions of longitudinal adjustment relative to 7 the subframe, and when the nut 72 is tightened down against the spring 73, the scale 66 will be locked in a selected position of longitudinal adjustment relative to the subframe. It will be noted that the subframe 63 is of elongated, rectangular shape and has a surrounding flange 75 perpendicular to the web 76 thereof and has straight and parallel end surfaces 77 and 78 which are respectively in the planes of the side surfaces 44 and 45 of the main frame 41 so that both of the scales and 66 can be similarly adjusted relative to the planes of the side surfaces of the main frame.

The scale 66 has rectangular notches 80 and 81 disposed one at each end of the scale symmetrically of the longitudinal center line of the latter and has scales of lineal measurement, as indicated at 82 and 83, extending along the longitudinal edges thereof. The scales of lineal measurement on the smaller scale or scale bar 66 begin and terminate at the inner ends of the notches 80 and 81 and each of these scales has at its starting end a zero line 84 and blank spaces of one eighth inch disposed one at each side of the zero line to assist in positioning the scale of lineal measurement on the scale bar 50 nearest the scale bar 66 at a preselected position relative to the scale of lineal measurement on the scale bar 66 nearest the scale bar 50 for a purpose which will presently appear.

The main frame 41 has a socket extending longitudinally thereof and opening to the end thereof remote from the notch 46 and a metal scribing tool 85 is disposed in this socket with one end projecting from the end of the main frame to which the socket opens, this tool being removable from the main frame whenever it is needed to inscribe marks or lines on the sheet metal work piece.

After the blank 37 has been cut out, as illustrated in Figure 3, the scale 50 is set relative to the main frame 41 so that it extends from one side of the main frame a distance exactly equal to the distance between a selected side edge of the blank and the fold line adjacent this side edge and is locked in this position. Then, with the corresponding side of the tool frame 41 resting against the selected outer edge of the blank, lines are inscribed on the blank near opposite corners thereof and this process is repeated around the blank, readjusting the scale 50, if necessary, for the different outside edges of the blank, until the four corners of the rectangular intermediate or base portion 15' of the blank have been located as indicated at 86, 87, 88 and 89 in Figure 3 by the intersections of scribed lines adjacent the corners of the blank. By joining the corner marks of the base portion along the corresponding sides of the blank with a straight edge, fold lines are now scribed on the blank, as indicated at 90, 91, 92 and 93 in Figure 4 outlining the intermediate base portion 15 and the end and side wall portions and the corners of the blank are now cut away to free the side and end wall portions 16, 17', 18 and 19' so that these portions can later be bent to a position at which they extend perpendicularly from one side of the base portion 15' to constitute the completed receptacle.

After the fold lines to 93 inclusive have been laid out on the blank and the corners of the blank cut away, as described above, the next step will be to locate the centers of all of the circular holes in the blank and the corners of all of the straight sided holes. One of the fold lines shown on the working drawing 10, from which measurements to the centers and corners of the holes are indicated, is now selected and the scale 66 is adjusted longitudinally through the subframe 63 to a distance corresponding to the width of the side or end portion of the blank along the selected fold line. This adjustment is made so that with one side of the frame 41 and the corresponding end of the frame 63 hearing against the selected outside edge of the blank, an end portion of the scale 66 will extend across the corresponding side or end member and the end of this scale will be so positioned that the inner end of the rectangular notch in this end of the scale will be coincident with the selected fold line. A dimension from the selected fold line to the center of a circular opening or to one corner of a straight sided opening is now selected from the working drawing 10 and the scale 50 is adjusted longitudinally to the frame 41 so that it extends beyond the end of the scale 66 adjusted to the selected fold line a distance equal to the selected dimension. The scale 50 is so adjusted that the point on its scale of lineal measurement adjacent the scale 66 corresponding to the dimension selected from the working drawing is on a line extending transversely of the two scales and along the inner end of the rectangular notch in the corresponding end of the pre-set scale 66, the emphasized scale mark 84 on the scale 66 being utilized to facilitate obtaining this adjustment with extreme accuracy.

With the frame of the tool resting against the selected side edge of the blank, marks are now scribed on the blank to locate the centers and corners of the holes at the proper distance from the selected fold line, the scale 50 being readjusted relative to the scale 66 as may be necessary. After all of the dimensions from the selected fold line have been marked on the blank, a fold line at right angles to the first selected fold line is now selected and dimensions, as given on the working drawing, measured from the second selected fold line are marked on the blank in a similar manner by lines intersecting the lines first provided on the blank at the proper locations to give the centers of the circular holes or openings, as indicated at 95 in Figure 4 and the corners of the straight sided openings, as indicated at 96. The blank may now be marked with the diametrical dimensions of the circular openings adjacent the corresponding center marks for these openings and the corners of the straight sided openings may be connected to show these openings in outline.

The blank is now drilled, punched or otherwise worked to provide the circular and straight sided openings therein as indicated at 97, and 98 in Figure 5, openings, as indicated at 99, being also located and provided in the side and end wall portions of the blank in a similar manner, if such opening are shown on the working drawing.

After the openings have been provided in the blank the side and end wall portions 16 to 19' inclusive are folded along the corresponding fold lines until they extend perpendicularly from one side of the base portion 15' of the blank to form the completed receptacle, the adjoining ends of the side and end wall portions being secured together, if desired, by suitable means such as soldering, beading or riveting.

Instead of being used to form a receptacle or other structure directly, the completed blank may constitute a template for laying out other work pieces. in this case, instead of drilling out the circular openings to full size, a small center hole will be provided concentric with the center of each circular opening to receive a transfer punch for marking the centers of the circular openings on the work pieces.

By using the improved measuring tool in the above described method the dimensions given on the working drawing can be quickly and accurately transferred to the sheet metal blank and the diagram of the drawing reproduced on the blank in a manner such that the blank can be accurately cut and punched to provide a high precision receptacle for special use, such as to constitute the chassis of an electronic device.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims, are therefore, intended to be embraced therein.

Wht is claimed is:

1. A method of manufacturing a precision receptacle which comprises the steps of accurately cutting to drawing dimensions a rectangular sheet metal receptacle blank whose outline includes major exterior edges of the blank; scribing on said blank fold lines to form a rectangular outline oriented accurately with respect to the blank edges according to dimensions given upon the working drawing; setting on a measuring tool having two slidably adjustable scales perpendicular to a flat bearing surface in a frame, the zero edge of one scale to register with a selected one of said fold lines when the frame of the bearing surface of the tool is in bearing contact with the adjacent edge of the blank; pro-setting the other scale of said tool so that its zero edge lies beyond the zero edge of the first scale a distance designated on the drawing for a critical point of an aperture with respect to the fold line; setting the tool with the frame in bearing contact with the blank edge; scribing a line coinciding with the Zero edge of the second scale on the blank; by similar procedure involving no change in the setting of the first scale, scribing other lines according to drawing dimensions for critical points of other apertures with respect to the same fold line; and removing the metal with respect to the marked critical point intersections to form apertures.

2. A method of manufacturing a precision receptacle which comprises the steps of accurately cutting to drawing dimensions a rectangular sheet metal receptacle blank whose outline includes major exterior edges of the blank; scribing on said blank fold lines to form a rectangular outline oriented accurately with respect to the blank edges according to dimensions given upon the working drawing; setting on a measuring tool having two slidably adjustable scales perpendicular to a flat bearing surface in a frame, the zero edge of one scale to register with a selected one of said fold lines when the frame of the bearing surface of the tool is in bearing contact with the adjacent edge of the blank; pre-setting the other scale of said tool so that its zero edge lies beyond the zero edge of the first scale a distance designated on the drawing for a critical point of an aperture with respect to the fold line; setting the tool with the frame in bearing contact with the blank edge; scribing a line coinciding with the zero edge of the second scale on the blank; by similar procedure involving no change in the setting of the first scale, scribing other lines according to drawing dimensions for critical points of other apertures with respect to the same fold line; scribing intersecting lines for the same critical aperture points by a similar procedure with respect to a second fold line; and removing the metal with respect to the marked critical point intersections to form apertures.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 385,321 Pickering June 26, 1888 728,790 West May 19, 1903 1,379,253 Dorney May 24, 1921 1,509,703 Bourgeois Sept. 23, 1924 1,676,298 Stieglitz July 10, 1928 2,175,650 Schaber Oct. 10, 1939 

